Techniques and instrumentation for the cystoscopic removal of ureteral calculi have been well documented in the medical literature and perhaps to a lesser extent in patent literature. Although procedures have varied, most of them have involve dilatating, anesthetizing and lubricating the ureter and then attempting to grasp the calculus and either crush it or drag it out. One such early device, disclosed in Cecil U.S. Pat. No. 1,612,697, took the form of a flexible tubing through which at least a pair of wires extended, the wires being formed at their distal ends to define a basket or cage for ensnaring ureteral calculi. Shortly thereafter, Vose modified the Cecil instrument to provide a cage composed of four wires, such wires spreading to form the cage, upon emergence from the tube, because of the natural springiness of those wires. (N.E.J. of M., Vol. 198, No. 12, 638-639 (1928)). Somewhat similar instruments were developed by Councill, Johnson, Morton, and others. (Jour. A.M.A., 1907-1909 (1926); J. Urol., Vol. 37, 84-89 (1937); J. Urol., Vol. 60, 242-243 (1948); Councill U.S. Pat. No. 1,677,671). More recent variations have included spiral extractor configurations to promote effective grasping and withdrawal of the calculi (Jour. A.M.A. Vol. 114, pp. 6-12 (1940); J. Urol., Vol. 40, 83-100 (1938); Dormia U.S. Pat. No. 2,943,626).
Although ultrasound is rapidly finding increasing use in medicine, its use in the genitourinary tract has mainly been limited to examination of renal and bladder lesions. Lamport and Newman may have been the first to consider ultrasonic lithotresis, successfully performing laboratory experiments in breaking or disintegrating stones in the ureters of dogs and cadavers (Yale J. Biol. Med. Vol. 27, 395 (1955); J. Urol. Vol. 70, 704 (1953)). In 1973, Goodfriend published the first successful ultrasonic disintegration and removal of an impacted ureteral stone from a patient (Urology, Vol. 1, No. 3, 260 (1973).